The instant invention relates to a stacking and surface protection device on a protective housing made of a synthetic material.
In chemical and refining plants, field instruments are generally built into protective housings made of a synthetic material in order to protect them from climatic influences and corrosive substances to ensure their proper operation and long tool life.
The outer surfaces of the protective housings are generally made to be as smooth as possible. The advantage of this over rough surfaces is that rain water runs off easily, that less dirt is deposited and that overall corrosion resistance is increased.
However, these advantages are also coupled with disadvantages that have been accepted until now. The smooth synthetic material surfaces are easily scratched during manufacture, warehousing, assembly, repair, etc., so that the aspect of the housings suffers. In the past, the housings were set down on a flat outer surface so that, in addition to the danger of scratching, the surfaces on which the housings are deposited are easily soiled, as in the case of repair, on a dirty or oily work bench.
Stackability of complete protective housings in the form of paralellepipeds is a special problem. It can easily be seen that until now only little friction is produced between two smooth contact surfaces in stacking, so that if the supporting surface is even slightly slanted, or if lateral forces are exerted, the stacked housings are shifted in relation to each other so that storage and transportation is impossible without using additional means. Until now, for instance, expensive support skeletons were used, together with welded foil packing, to prevent a stack from collapsing and to make transportation in a stacked condition possible at all.
Many different stacking and antislipping devices on housings are known. Known loud-speaker housings have supporting feet on their underside, near the corners, and are provided with corresponding depressions on their upper surface. When identical housings are stacked together into a so-called loud-speaker tower, the supporting feet enter into the depressions and act as antislipping devices. With such an arrangement the lower support surface with the supporting feet and the upper surface are fixed. If such a housing were to be set down upside-down, with the upper surface down, that surface would be scratched because of the missing protrusions.
Other stacking and antislipping devices consist of raised supports on both the lower and the upper surface. Here the "male" supports on the upper surface, located slightly further inside, reach into the "female" supports located further out. Slippage is thus prevented by common contact surfaces. But since the male or female supports are attached either on the lower or on the upper surface, these surfaces are necessarily different in configuration. When two surfaces of identical configuration are used, these can obviously not interlock by means of their antislipping devices.
However, known protective housings consist of two or more bottom and cover elements. These elements are of different depths, and by using different combinations they can be put together into more or less deep protective cases, depending upon the application. This means, for instance, that when identical cover elements of equal depth are assembled, the bottom and the cover surfaces are identical in configuration. Depending upon the application, a deep or flat protection case element can also be used as a bottom or cover element, so that one and the other surface alternately becomes the bottom or the cover surface.
Due to this fact it is not possible to use the above-described, known stacking and antislipping devices which would require a fixed designation of the bottom or cover surface and different configurations.
Accordingly, an object of the instant invention is to create a stacking and surface protection device on a protective housing made of a synthetic material that simply and inexpensively serves as a protector of delicate smooth surfaces, furthermore makes stable stacking possible and prevents mutual shifting of two protective housings stacked on top of each other while the surfaces are of identical configuration.